Do crocodile smiles hold the secret to regrowing teeth?

Crocodiles and some of their plant-eating ancestors have thin tooth enamel, a trait that is in stark contrast to humans and other hard-biting species, according to new research.

These findings could suggest new approaches for dealing with people’s teeth.

Crocodiles have one of the most powerful bites in the animal kingdom, which is necessary to chow down on turtles, wildebeest, and other large prey. Rather than clean their teeth to slow down wear and tear, crocodiles just grow new ones.

“Once we unlock genetically how crocodiles and other non-mammals do this, maybe new teeth can be bioengineered for people,” says Brianne Schmiegelow, a former undergraduate student at the University of Missouri and currently a dental student at the University of Missouri-Kansas City. “Instead of using fillers such as crowns, people could instead ‘grow’ new teeth when they need to replace their worn out chompers.”

Using a three-dimensional x-ray scanner, researchers discovered that crocodiles don’t have thick tooth enamel, regardless of tooth position—incisor, canine, molar—age, or diet.

With this new information, the team also studied published data on dinosaur teeth and found that the data nearly matched what they were seeing in crocodiles. For instance, a Tyrannosaurus rex has the same enamel thickness as a crocodile and can also bite extremely hard.

“Crocodiles bite really hard, so we were curious if they have teeth that correspondingly withstand those forces—tough teeth to match a tough bite,” says Kaleb Sellers, a postdoctoral fellow in the School of Medicine and lead researcher of the study in the Journal of Zoology.

“We found that they don’t have tough teeth, and we think it’s because they replace their teeth like most other non-mammal animals. That made us wonder if other animals—even prehistoric—had similar issues.”

The next step is to study tooth replacement and the timing of teeth growth in crocodiles and other animals such as dinosaurs—even looking into the possibility of genetic causes.

“Enamel takes a long time to build, so it’s not something animals will do ‘off-the-cuff,’ so to speak,” says Casey Holliday, an associate professor of anatomy.

“It presents us with an interesting puzzle. If ancient crocodiles were chewing plants, did their new teeth already have the correct architecture—dimples and facets—to allow for this chewing? The findings here have paved the way for exploring this mystery with future research.”

The National Science Foundation, the University of Missouri Research Board, the University of Missouri Research Council, and the University of Missouri Life Sciences Undergraduate Research Opportunity program funded the work. The content is solely the responsibility of the authors and does not necessarily represent the official views of the funding agencies.

Source: University of Missouri